Gauge Scale not Working

Hi I actually followed this link for creating a gauge view.

http://mindtherobot.com/blog/272/android-custom-ui-making-a-vintage-thermometer/

But when I run the code in the emulator, the readings of the gauge turn out to be zero and I am not able to figure out why. Any clues on what could have gone wrong? I printed the "i" values of the function drawscale and they turn out to be fine but the reading in the gaugeview when I run the emulator always is zero.

      package com.mindtherobot.samples.thermometer;


      import java.util.List;

     import android.content.Context;
     import android.graphics.Bitmap;
     import android.graphics.BitmapFactory;
     import android.graphics.BitmapShader;
     import android.graphics.Canvas;
     import android.graphics.Color;
     import android.graphics.LightingColorFilter;
     import android.graphics.LinearGradient;
     import android.graphics.Matrix;
     import android.graphics.Paint;
     import android.graphics.Path;
     import android.graphics.RadialGradient;
     import android.graphics.RectF;
     import android.graphics.Shader;
     import android.graphics.Typeface;
     import android.hardware.Sensor;
     import android.hardware.SensorEvent;
     import android.hardware.SensorEventListener;
     import android.hardware.SensorManager;
      import android.os.Bundle;
      import android.os.Handler;
    import android.os.Parcelable;
    import android.util.AttributeSet;
    import android.util.Log;
    import android.view.View;

    public final class Thermometer extends View implements SensorEventListener {

private static final String TAG = Thermometer.class.getSimpleName();

private Handler handler;

// drawing tools
private RectF rimRect;
private Paint rimPaint;
private Paint rimCirclePaint;

private RectF faceRect;
private Bitmap faceTexture;
private Paint facePaint;
private Paint rimShadowPaint;

private Paint scalePaint;
private RectF scaleRect;

private Paint titlePaint;   
private Path titlePath;

private Paint logoPaint;
private Bitmap logo;
private Matrix logoMatrix;
private float logoScale;

private Paint handPaint;
private Path handPath;
private Paint handScrewPaint;

private Paint backgroundPaint; 
// end drawing tools

private Bitmap background; // holds the cached static part

// scale configuration


private int totalNotches = 100;
private int incrementPerLargeNotch = 10;
private int incrementPerSmallNotch = 2;
private float degreesPerNotch = 360.0f / totalNotches;  

private int scaleCenterValue = 40; // the one in the top center (12 o'clock)
private int scaleMinValue = -30;
private int scaleMaxValue = 110;

// hand dynamics -- all are angular expressed in F degrees
private boolean handInitialized = false;
private float handPosition = scaleCenterValue;
private float handTarget = scaleCenterValue;
private float handVelocity = 0.0f;
private float handAcceleration = 0.0f;
private long lastHandMoveTime = -1L;


public Thermometer(Context context) {
    super(context);
    init();
}

public Thermometer(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
}

public Thermometer(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init();
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    attachToSensor();
}

@Override
protected void onDetachedFromWindow() {
    detachFromSensor();
    super.onDetachedFromWindow();
}

@Override
protected void onRestoreInstanceState(Parcelable state) {
    Bundle bundle = (Bundle) state;
    Parcelable superState = bundle.getParcelable("superState");
    super.onRestoreInstanceState(superState);

    handInitialized = bundle.getBoolean("handInitialized");
    handPosition = bundle.getFloat("handPosition");
    handTarget = bundle.getFloat("handTarget");
    handVelocity = bundle.getFloat("handVelocity");
    handAcceleration = bundle.getFloat("handAcceleration");
    lastHandMoveTime = bundle.getLong("lastHandMoveTime");
}

@Override
protected Parcelable onSaveInstanceState() {
    Parcelable superState = super.onSaveInstanceState();

    Bundle state = new Bundle();
    state.putParcelable("superState", superState);
    state.putBoolean("handInitialized", handInitialized);
    state.putFloat("handPosition", handPosition);
    state.putFloat("handTarget", handTarget);
    state.putFloat("handVelocity", handVelocity);
    state.putFloat("handAcceleration", handAcceleration);
    state.putLong("lastHandMoveTime", lastHandMoveTime);
    return state;
}

private void init() {
    handler = new Handler();

    initDrawingTools();
}

private String getTitle() {
    return "mindtherobot.com";
}

private SensorManager getSensorManager() {
    return (SensorManager) getContext().getSystemService(Context.SENSOR_SERVICE);       
}

private void attachToSensor() {
    SensorManager sensorManager = getSensorManager();

    List<Sensor> sensors = sensorManager.getSensorList(Sensor.TYPE_TEMPERATURE);
    if (sensors.size() > 0) {
        Sensor sensor = sensors.get(0);
        sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_FASTEST, handler);
    } else {
        Log.e(TAG, "No temperature sensor found");
    }       
}

private void detachFromSensor() {
    SensorManager sensorManager = getSensorManager();
    sensorManager.unregisterListener(this);
}

private void initDrawingTools() {
    rimRect = new RectF(0.1f, 0.1f, 0.9f, 0.9f);

    // the linear gradient is a bit skewed for realism
    rimPaint = new Paint();
    rimPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
    rimPaint.setShader(new LinearGradient(0.40f, 0.0f, 0.60f, 1.0f, 
                                       Color.rgb(0xf0, 0xf5, 0xf0),
                                       Color.rgb(0x30, 0x31, 0x30),
                                       Shader.TileMode.CLAMP));     

    rimCirclePaint = new Paint();
    rimCirclePaint.setAntiAlias(true);
    rimCirclePaint.setStyle(Paint.Style.STROKE);
    rimCirclePaint.setColor(Color.argb(0x4f, 0x33, 0x36, 0x33));
    rimCirclePaint.setStrokeWidth(0.005f);

    float rimSize = 0.02f;
    faceRect = new RectF();
    faceRect.set(rimRect.left + rimSize, rimRect.top + rimSize, 
             rimRect.right - rimSize, rimRect.bottom - rimSize);        

    faceTexture = BitmapFactory.decodeResource(getContext().getResources(), 
               R.drawable.plastic);
    BitmapShader paperShader = new BitmapShader(faceTexture, 
                                                Shader.TileMode.MIRROR, 
                                                Shader.TileMode.MIRROR);
    Matrix paperMatrix = new Matrix();
    facePaint = new Paint();
    facePaint.setFilterBitmap(true);
    paperMatrix.setScale(1.0f / faceTexture.getWidth(), 
                         1.0f / faceTexture.getHeight());
    paperShader.setLocalMatrix(paperMatrix);
    facePaint.setStyle(Paint.Style.FILL);
    facePaint.setShader(paperShader);

    rimShadowPaint = new Paint();
    rimShadowPaint.setShader(new RadialGradient(0.5f, 0.5f, faceRect.width() / 2.0f, 
               new int[] { 0x00000000, 0x00000500, 0x50000500 },
               new float[] { 0.96f, 0.96f, 0.99f },
               Shader.TileMode.MIRROR));
    rimShadowPaint.setStyle(Paint.Style.FILL);

    scalePaint = new Paint();
    scalePaint.setStyle(Paint.Style.STROKE);
    scalePaint.setColor(0x9f004d0f);
    scalePaint.setStrokeWidth(0.005f);
    scalePaint.setAntiAlias(true);

    scalePaint.setTextSize(0.045f);
    scalePaint.setTypeface(Typeface.SANS_SERIF);
    scalePaint.setTextScaleX(0.8f);
    scalePaint.setTextAlign(Paint.Align.CENTER);        

    float scalePosition = 0.10f;
    scaleRect = new RectF();
    scaleRect.set(faceRect.left + scalePosition, faceRect.top + scalePosition,
                  faceRect.right - scalePosition, faceRect.bottom - scalePosition);

    titlePaint = new Paint();
    titlePaint.setColor(0xaf946109);
    titlePaint.setAntiAlias(true);
    titlePaint.setTypeface(Typeface.DEFAULT_BOLD);
    titlePaint.setTextAlign(Paint.Align.CENTER);
    titlePaint.setTextSize(0.05f);
    titlePaint.setTextScaleX(0.8f);

    titlePath = new Path();
    titlePath.addArc(new RectF(0.24f, 0.24f, 0.76f, 0.76f), -180.0f, -180.0f);

    logoPaint = new Paint();
    logoPaint.setFilterBitmap(true);
    logo = BitmapFactory.decodeResource(getContext().getResources(), R.drawable.logo);
    logoMatrix = new Matrix();
    logoScale = (1.0f / logo.getWidth()) * 0.3f;;
    logoMatrix.setScale(logoScale, logoScale);

    handPaint = new Paint();
    handPaint.setAntiAlias(true);
    handPaint.setColor(0xff392f2c);     
    handPaint.setShadowLayer(0.01f, -0.005f, -0.005f, 0x7f000000);
    handPaint.setStyle(Paint.Style.FILL);   

    handPath = new Path();
    handPath.moveTo(0.5f, 0.5f + 0.2f);
    handPath.lineTo(0.5f - 0.010f, 0.5f + 0.2f - 0.007f);
    handPath.lineTo(0.5f - 0.002f, 0.5f - 0.32f);
    handPath.lineTo(0.5f + 0.002f, 0.5f - 0.32f);
    handPath.lineTo(0.5f + 0.010f, 0.5f + 0.2f - 0.007f);
    handPath.lineTo(0.5f, 0.5f + 0.2f);
    handPath.addCircle(0.5f, 0.5f, 0.025f, Path.Direction.CW);

    handScrewPaint = new Paint();
    handScrewPaint.setAntiAlias(true);
    handScrewPaint.setColor(0xff493f3c);
    handScrewPaint.setStyle(Paint.Style.FILL);

    backgroundPaint = new Paint();
    backgroundPaint.setFilterBitmap(true);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    Log.d(TAG, "Width spec: " + MeasureSpec.toString(widthMeasureSpec));
    Log.d(TAG, "Height spec: " + MeasureSpec.toString(heightMeasureSpec));

    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);

    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);

    int chosenWidth = chooseDimension(widthMode, widthSize);
    int chosenHeight = chooseDimension(heightMode, heightSize);

    int chosenDimension = Math.min(chosenWidth, chosenHeight);

    setMeasuredDimension(chosenDimension, chosenDimension);
}

private int chooseDimension(int mode, int size) {
    if (mode == MeasureSpec.AT_MOST || mode == MeasureSpec.EXACTLY) {
        return size;
    } else { // (mode == MeasureSpec.UNSPECIFIED)
        return getPreferredSize();
    } 
}

// in case there is no size specified
private int getPreferredSize() {
    return 300;
}

private void drawRim(Canvas canvas) {
    // first, draw the metallic body
    canvas.drawOval(rimRect, rimPaint);
    // now the outer rim circle
    canvas.drawOval(rimRect, rimCirclePaint);
}

private void drawFace(Canvas canvas) {      
    canvas.drawOval(faceRect, facePaint);
    // draw the inner rim circle
    canvas.drawOval(faceRect, rimCirclePaint);
    // draw the rim shadow inside the face
    canvas.drawOval(faceRect, rimShadowPaint);
}

private void drawScale(Canvas canvas) {
    // Draw a large notch every large increment, and a small
    // notch every small increment.

    canvas.drawOval(scaleRect, scalePaint);

    canvas.save(Canvas.MATRIX_SAVE_FLAG);
    for (int i = 0; i < totalNotches; ++i) {
        float y1 = scaleRect.top;
        float y2 = y1 - 0.015f;
        float y3 = y1 - 0.025f;
        System.out.println("The value of i is "+i);

        int value = notchToValue(i);
        System.out.println("The value of value is "+value);
        if (i % (incrementPerLargeNotch/incrementPerSmallNotch) == 0) {
            System.out.println("inside loop i"+i);
            if (value >= scaleMinValue && value <= scaleMaxValue) {
                // draw a nick
                canvas.drawLine(0.5f, y1, 0.5f, y3, scalePaint);

                String valueString = Integer.toString(value);
                System.out.println("the value of value string is "+valueString);
                // Draw the text 0.15 away from y3 which is the long nick.
                canvas.drawText(valueString, 0.5f, y3 - 0.015f, scalePaint);
            }
        }
        else{
            if (value >= scaleMinValue && value <= scaleMaxValue) {
                // draw a nick
                canvas.drawLine(0.5f, y1, 0.5f, y2, scalePaint);
            }
        }

        canvas.rotate(degreesPerNotch, 0.5f, 0.5f);
    }
    canvas.restore();       
}

private int notchToValue(int value) {
    int rawValue = ((value < totalNotches / 2) ? value : (value - totalNotches)) * incrementPerSmallNotch;
    int shiftedValue = rawValue + scaleCenterValue;
    return shiftedValue;
}

private float valueToAngle(float value) {
    return (value - scaleCenterValue) / 2.0f * degreesPerNotch;
}
private void drawTitle(Canvas canvas) {
    String title = getTitle();
    canvas.drawTextOnPath(title, titlePath, 0.0f,0.0f, titlePaint);             
}

private void drawLogo(Canvas canvas) {
    canvas.save(Canvas.MATRIX_SAVE_FLAG);
    canvas.translate(0.5f - logo.getWidth() * logoScale / 2.0f, 
                     0.5f - logo.getHeight() * logoScale / 2.0f);

    int color = 0x00000000;
    float position = getRelativeTemperaturePosition();
    if (position < 0) {
        color |= (int) ((0xf0) * -position); // blue
    } else {
        color |= ((int) ((0xf0) * position)) << 16; // red          
    }
    //Log.d(TAG, "*** " + Integer.toHexString(color));
    LightingColorFilter logoFilter = new LightingColorFilter(0xff338822, color);
    logoPaint.setColorFilter(logoFilter);

    canvas.drawBitmap(logo, logoMatrix, logoPaint);
    canvas.restore();       
}

private void drawHand(Canvas canvas) {
    if (handInitialized) {
        float handAngle = valueToAngle(handPosition);
        canvas.save(Canvas.MATRIX_SAVE_FLAG);
        canvas.rotate(handAngle, 0.5f, 0.5f);
        canvas.drawPath(handPath, handPaint);
        canvas.restore();

        canvas.drawCircle(0.5f, 0.5f, 0.01f, handScrewPaint);
    }
}

private void drawBackground(Canvas canvas) {
    if (background == null) {
        Log.w(TAG, "Background not created");
    } else {
        canvas.drawBitmap(background, 0, 0, backgroundPaint);
    }
}

@Override
protected void onDraw(Canvas canvas) {
    drawBackground(canvas);

    float scale = (float) getWidth();       
    canvas.save(Canvas.MATRIX_SAVE_FLAG);
    canvas.scale(scale, scale);

    drawLogo(canvas);
    drawHand(canvas);

    canvas.restore();

    if (handNeedsToMove()) {
        moveHand();
    }
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    Log.d(TAG, "Size changed to " + w + "x" + h);

    regenerateBackground();
}

private void regenerateBackground() {
    // free the old bitmap
    if (background != null) {
        background.recycle();
    }

    background = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
    Canvas backgroundCanvas = new Canvas(background);
    float scale = (float) getWidth();       
    backgroundCanvas.scale(scale, scale);

    drawRim(backgroundCanvas);
    drawFace(backgroundCanvas);
    drawScale(backgroundCanvas);
    drawTitle(backgroundCanvas);        
}

private boolean handNeedsToMove() {
    return Math.abs(handPosition - handTarget) > 0.01f;
}

private void moveHand() {
    if (! handNeedsToMove()) {
        return;
    }

    if (lastHandMoveTime != -1L) {
        long currentTime = System.currentTimeMillis();
        float delta = (currentTime - lastHandMoveTime) / 1000.0f;

        float direction = Math.signum(handVelocity);
        if (Math.abs(handVelocity) < 90.0f) {
            handAcceleration = 5.0f * (handTarget - handPosition);
        } else {
            handAcceleration = 0.0f;
        }
        handPosition += handVelocity * delta;
        handVelocity += handAcceleration * delta;
        if ((handTarget - handPosition) * direction < 0.01f * direction) {
            handPosition = handTarget;
            handVelocity = 0.0f;
            handAcceleration = 0.0f;
            lastHandMoveTime = -1L;
        } else {
            lastHandMoveTime = System.currentTimeMillis();              
        }
        invalidate();
    } else {
        lastHandMoveTime = System.currentTimeMillis();
        moveHand();
    }
}

@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {

}

@Override
public void onSensorChanged(SensorEvent sensorEvent) {
    if (sensorEvent.values.length > 0) {
        float temperatureC = sensorEvent.values[0];
        //Log.i(TAG, "*** Temperature: " + temperatureC);

        float temperatureF = (9.0f / 5.0f) * temperatureC + 32.0f;
        setHandTarget(temperatureF);
    } else {
        Log.w(TAG, "Empty sensor event received");
    }
}

private float getRelativeTemperaturePosition() {
    if (handPosition < scaleCenterValue) {
        return - (scaleCenterValue - handPosition) / (float) (scaleCenterValue - scaleMinValue);
    } else {
        return (handPosition - scaleCenterValue) / (float) (scaleMaxValue - scaleCenterValue);
    }
}

private void setHandTarget(float temperature) {
    if (temperature < scaleMinValue) {
        temperature = scaleMinValue;
    } else if (temperature > scaleMaxValue) {
        temperature = scaleMaxValue;
    }
    handTarget = temperature;
    handInitialized = true;
    invalidate();
}

}

I know this is an old question, but I encountered the same problem yesterday.

What I believe the OP is describing is that all the number values displayed on the scale appear to be 0. Setting setLinearText(true) to scalePaint corrected this.